spoke length question
I am building up a wheel with a nuvinci hub and a 650B rim (ERD= 566), this is basically a symmetrical wheel as there is no need for dish, at issue is that each flange diameter is 125 mm, the manual recommends building the wheel cross TWO, is this because, as the flange is so large, if you build a cross 3, will the spoke head at the rim will be at an adverse angle?
Basically, what is the relationship between hub flange diameter and recommended cross pattern, are they related?